New Laptop, Question on Battery

crisp

Im getting a new laptop this week. Is there a requirement to charge the battery before first use to get the maximum out of it over the longer term or just urban myth?

Its a Dell

StuC75

Laptops are designed to be still used while they are on charge.. If they are used as a desktop replacement, then some people do suggest that the battery should be removed so that doesn't affect the charge\discharge circuit - although in that case a powercut \ nudge of the power cable will turn it straight off..

So in part it may depend on how you are likely to use the laptop?..

esuhl

Laptops tend to use lithium-ion (Li-ion) cells these days, which don't suffer from the "memory effect" of nickel-cadmium (Ni-Cd) and (to a lesser extent) nickel-metal hydride (Ni-MH) cells. So you don't need to worry (so much) about charging them fully, then discharging them fully each time.

I'm not sure if it's true, but most of the Li-ion devices I've bought have said that they should be put on charge (until full) the first time you use them, and that they take 5 or 6 charge/discharge cycles before they reach their maximum capacity (which then reduces as the cells become stressed).

Li-ion cells are particularly sensitive to temperature (anything over 30C and their performance really deteriorates). High charges and rapid discharging can also stress them.

For storage, Li-ion cells are best kept cool (i.e. in the fridge) and charged to about 35% of their usable capacity. Keeping unused batteries fully charged at high temperatures will cause them to degrade much more rapidly. However, batteries slowly discharge themselves over time and with Li-ion batteries, if the charge drops too low the resistance of the cell increases so much that charging would increase the risk of explosion. For this reason, there's some clever circuitry in laptops to prevent this, but it does mean that if your cell is left with very little charge for a long period of time, the charger/laptop will refuse to charge it. So... store the batter with too little charge and it becomes unusable; store it with too much and it will degrade faster.

Dunno if any of that helps, but there's some great information (amongst the jargon) at the Battery University:

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

Dollardog

esuhl - I mislaid the battery to my laptop ages ago and as I only use it as a desktop always plugged into the mains, its never really been a problem, but if I found it, what you seem to be saying is it probably wouldn't be any good now anyway as it would have run out of charge?

AltheBiker

Always fully charge ANY battery if you can before first use. It does help. Also do not leave your power lead in all the time constantly trickle charging the battery, it will considerably lessen the battery's overall life and its usage life. Let the laptop run on battery a lot of the time, its cheaper anyway.

esuhl

AltheBiker wrote: »

Always fully charge ANY battery if you can before first use. It does help. Also do not leave your power lead in all the time constantly trickle charging the battery, it will considerably lessen the battery's overall life and its usage life. Let the laptop run on battery a lot of the time, its cheaper anyway.

Yup -- keeping the battery fully charged all the time will cause it to "wear out" quicker.

Dollardog wrote: »

esuhl - I mislaid the battery to my laptop ages ago and as I only use it as a desktop always plugged into the mains, its never really been a problem, but if I found it, what you seem to be saying is it probably wouldn't be any good now anyway as it would have run out of charge?

Wellll... as the battery discharges, the internal resistance increases, which slows down the rate of discharge... so... I think it's a logarithmic function. So... the battery would probably survive for a fair while (years?). It will be continually degrading no matter what you do, but being stored highly charged or at high temperature will cause that degradation to happen more quickly.

Batteries need a fair bit of charge to be functional, so when your laptop says you have 5% charge remaining, that's 5% usable charge. The battery might need to be 75% charged to work at all (i.e. to register 0% on your laptop), and it might be safe to recharge at anything above 30% charge (or minus 80% as far as your laptop display is concerned).

Best thing would be to let it adjust to room temperature (If it's been stored somewhere cool or hot), and fully re-charge it before use.

Apparently, if you are going to store the batteries, it's worth getting them out every now and then (once or twice a year?), charging them up and using them a few times (discharging/recharging) before putting them away again.

Coincidentally, I've just been looking for bike lights and came across this comment about Li-ion cells:

You can expect five years of optimal operation from a lithium-ion battery. After approximately 400 charge–discharge cycles the battery capacity will reduce to 80 per cent. Near freezing temperature causes 5–10% decrease in capacity and in heat over 40 degrees Celcius batteries permanently lose capacity at a rate of 5% per day.

http://rideons.wordpress.com/2013/05/07/top-60-lights-for-commuting-2013/